Uhf television tuner



April 27, 1965 R. c. A. ELAND U.H.F. TELEVISION TUNER 4 Sheets-Sheet 1Filed June 22, 1960 April 27, 1965 R. c. A. ELAND U.H.F. TELEVISIONTUNER 4 Sheets-Sheet 2 Filed June 22, 1960 INVENTOR. ,M55/e7 6,4. ,Q4/v0BY ?.Z-E'- 5. kreuze/maas@ ffag'frav April 27, 1965 R. c. A. ELAND-UJLF. TELEVISION TUNER vFiled June 22. 1960 4 Sheets-Sheet 3 April 27,1965 R. c. A. ELAND 3,181,069

U H. F TELEVISION TUNER Filed June 22. 1960 4 Sheets-Sheet 4 E .r 5. fl-5; 5.

United States Patent C) 3,181,069 UHF' TELEVlSlGN TUNER Robert C. A.Eland, Arcadia, Calif., assigner to Standard Coil Products Co., Inc.,Melrose Park, ill., a corporation of illinois Filed .lune 22, 1960, Ser.No. 38,018 1t) Claims. (Cl. S25-453) This invention relates to all-UHFtelevision tuner units, and more particularly relates to novelconstructions thereof with minimum oscillator radiation and reducedcost.

An all-UHF television tuner contains a tunable preselector and avariable oscillator to tune-in the 7 O channels over the 470 to 890 rnc.range. The UHF signals are circuitally contained in an enclosed metalchassis to reduce radiations. To minimize oscillator radiations, an RFamplifier stage is used, as is successfully done in VHF tuners. Agrounded-grid triode amplifier is operable over the UHF range, as is agrounded grid oscillator.

The present invention simpliies suchUHF tuner circuit by employing theoscillator triode stage as a mixer as well; and provides a novel zig-zagtunable line to permit reduced volumetric proportion. The result is agreatly reduced radiation ratio than heretofore attained.

It has heretofore been a tedious, skilled and costly process to build asmall UHF television tuner, with the components requiring precisedimensions, positions and wiring-in. 'Ihe present invention providesnovel and practical physical construction, and interrelation of thechassis and components.

The invention UHF tuner is composed of two major subassemblies readilyinsertable in a cover-box for simple precise final assembly. Thesubassemblies are mounted on chassis sub-units, wired-in and pretestedbefore nal assembly.

The chassis sub-units are arranged, with the inter-linked cover-box, toform novel inexpensive compartmentalized or isolated circuit sections.The result is substantially reduced cost of mass production of the UHFtuners, greatly increased uniformity ofrresults, minimum of tinal testtime and rejects. Each subassembly can be made on a line basis.

The chassis-box cover is formed in a novel manner, incorporating a wiremesh or screen on its inner face that presses againstthe edge of saidformed compartments to lshield against radiation.V

lt is accordingly an object of the present invention to provide a novelall-UHF television tuner.

Another object or" the present invention is to provide a novel allUHFtuner having erticient shielding to insure radiation while permittingreduced cost.

A further object of the present invention is-to provide a. novel all-UHFtuner with sub-unit constructions that are separably assembled andwired-in.

Still another obiect of the present invention is to provi e a novelall-UHF tuner with sub-chassis units arranged to form circuitcompartinentalization in a practical relatively inexpensive manner;

Still a furtherobject of the present invention is to provide a novelall-UHF tuner with a cover containing a wire mesh that inexpensivelyshield the tunerV compartments.

These and further objects of the invention will become more apparentfrom the following description Vof yan exemplary embodiment thereof,illustrated in the drawings in which: A

FLGURF. l is a circuit diagram of the exemplary i all-UHF tuner.

FGURE 2 is a side elevational view of the exemplary all-UHF tuner, withthe cover removed.

ice

FlGURES 3 and 4 are respective end and top views of the tuner of FIGURE2.

F GURE 5 is an interior plan view of the tuner cover, FGURE 6 being apartial cross-sectional view thereof across the line d-6.

vFFGURE 7 is a side elevational View of one subunit assembly of thetuner.

FIGURES 8, 9 and i0 are respective side, end and top views of anothersub-unit'assembly of the tuner.

FGURES 11 and 12 are diagramsV of the sub-unit arrangements, and theshield compartments formed thereby.

The diagram, FIGURE l, illustrates the several isolation or shieldcompartments 15 through 19 for the UHF tuner circuitry. There are twogrounded-grid triode stages 24d, 2l. The UHF antenna lead-ins connect toinput coil ZL., one end of which is coupled to the cathode input 23 ofRF amplifier stage 2t) through coupling condenser 24 and xed line 2.5.

A trimmer condenser 26 balances the input circuit. The tube Zd isinput-biased by a low value grounded resistor 27 to cathode 23 throughRF choke coil 23 and output section i6. The anode B-lsupply is shuntfedV to anode 32 from terminal feed-through 33 at chassis topplate 35,and RF choke 34. The RF output circuit in.

compartment' i6 comprises a .tuned line-variable condenser arrangement:line 3d coupled to anode '32 through feed-through condenser 39,'trimmercondensers or feedthroughs 37, 38 at each line end to ground at wall d,

and variable tuning condenser The physical length of fixed line Slt isproportioned to co-act with variable condenser di to permit tuning overthe 470 to 890 mc. range in of the condenser rotation.

in the exemplary embodiment, the line 36 was made offa silver-platedconductor, 17g" wide by l/gg thick, and 21/3 long. To save in the lineardimension 'to accommodate long line 36 in the chassis compartment 16,its over-all length was reduced to 11/2". This length reduction wasprovided by the zig-zag or pleated configuration shown in the tigures.rlChe effective inductive action of line 35 remains unimpaired by suchnovel arrangement.

The mixer input compartment l'7 is coupled to the RF compartment i6through a shaped aperture 42 of given area in the wall 4d between them(see also FIGURE 9). The tuned mixer input is composed of a zig-zag line43, end feed-through trirmners-d-i, d5, and tuning condenser 46. Themixer herein is combined in one triode stage 2l With the oscillator, Iasan autodyne circuit. The cathode 47 is connected .as the input, to aribbonld arranged close to, and along line 43 to couple therewith.Ribbon 48 17; A biasing resistor 5l connects cathode 47 :to the groundedwall E@ through ribbon 48. Y

The oscillator ltunable unit is composed of long zig-zag line 52, end'trimmers 53, 54, and series tuning condenser 55. The anode do isVcoupled tothe end of line 52 through a feed-through condenser 56. Theanode B+ supply is shunt fed .to electrode 55 from feed-throughcondenserv Y through dropping resistor 57, adjustable IF output coil 53,a seriesyof inter-compartment feed-through condensers Fatented Apr. 2?,1965 deleterious inter-coupling occurs in the intervening compartments.

The IF output compartment 19 contains the IF output coil 58, adjustablethrough exterior end projection, series condenser 66, and feed-throughterminal 67 in top chassis wall 35. A wall 70 isolates sections 15 and19. The

' bled compartments in an economical yet most effective (IF) outputcompartment 19 is lformed by shield wall f 70, part of partition wall30, part of top chassis plate 35, and an end wall 71. A bottom wall 72completes four sides of RF input section 15, together with walls 30 and70. Y

Section 16 contains part of cover bottom wall 75, part of chassissub-unit plate 35, and vertical Walls 30, 40. Similarly, compartment 17contains vertical walls 40 and 50, with vtop and bottom portions Iofplates 35 and 75. End section 18 contains wall 50, and Yend wall 50ofthe cover, with sections of plates 35 and 75. it is understood thatthe cover-box to be described, forms one side wall for sections 16, 17and 18, and ythe removable side cover to be shown hereinafter, shieldand seal the opposite vertical side of these sections, as well as thatof section 19.

FIGURES 2, 3 and 4 illustrate the exemplary tuner constructioncorresponding to the circuit of FIGURE l, like parts being identifiedwith the same numerals. The three .isolated vertical compartments 16,17, 18V house respectively the tunable RF amplifier Voutput, mixer inputand oscillator circuitry. The three ganged variable condensers 41, 46and 55 have a common tuning shaft 85. Shaft 85 projects through anaperture in wall 30 and is secured by washers 86, 87,'that in .turn sealthe aperture when brazed or soldered to wall 30.' A control gear 88,preferably of the anti-back lash type, is secured to and drives shaft85. The shaft 8S and the condenser rotor plates attached thereto are atthe case or ground potential.

The stator plates 41a, 46al and 55a Vof the condensers are insulatinglysupported on a transverse ceramic rod 90 mounted in present apertures incentral partitions 40, 50. The stators 41a, 46a, 55a tare supported bythe silvered bands 81, 82, 83 on'the rod 90, to which they are soldered.

The lower ends of the llines 36, 43, 52 are soldered to the f RF tube 20has the tube shield 20a (FIGURE 3); tube Y 21 has shieldr21a. Theseveral trimmer condensers are mounted with their respective adjustingscrews 26', 37', 44" and 53' shown projecting outside for accessibility.The antenna input section is constructed with a composition end-plate 91containing the lead-interminals V92, 92 (FIGURE 3). A tube heater supplyterminal 93 (FIG- URE 2) 'is shown on the chassis top 35. A mountingbracket 95 is attached t-o the base 75 exterior, having mounting holes96, 96, to prevent radiation through interior apertures.

A practical, inexpensive and novel cover 100 is used for the inventiontuner. Cover 100 is shown in partial View, in :position on the tuner inFIGURE 2, and in inside plan and sectional views in FIGURES 5 and-6respectively. Cover 100 lis composed of an outer metal sheet 101 and awatlled metal screen or mesh 102 on its inter-Y E the edgesV of cover107 mate with corresponding screw holes 105, 105 in the tuner frame (seeFIGURE 2) for screws 106 that attach them together.

The novel cover 100overlaps the basic tuner frame to the extent of itsfolded-overedges 103. In this way the soft screen mesh 102 is pressedagainst the adjacent edges fof the tuner frame and portions that formthe isolated sections 16, 17, 18, 19.V The mesh 102 serves toelectrically shield the portion edges to complete the assemmanner. Theresilience Iand resultant compliance of the metal mesh 102V 4pressed bythe cover body 101 against the edges of the compartments insures thefull electrical isolation.

An important feature of `the present invention are the novelsub-assembly structures that are separately assembled, wired in,soldered, and pre-tested before final interassembly for the inventionUHF tuner unit. FIGURE 7 illustrates the top-plate and tubesub-assembly. 110; FIG- URES 8, 9 and l0, the U-sub-chassis andcondenser gang assembly 120; and FIGURES 1l, 12 the manner of theirinterrelation to provide :the several isolated circuit compartments andthe UHF tuner construction hereof.

The top-plate sub-assembly 110 (FIGURE 7) includes the top chassissection 35 as seen in FIGURE l and a U-extension 111, 112 `jshown inFIGURE 7 integral at the RF end. Extension 111, 112 is proportioned toenclose the RF input compartment 15 and IF compartment 16 (seen inFGURES 1 and 2), when in final assembly against wall 30. A partitionshield 115 inside the extension 111, 112 establishes these tworelatively small adjacent compartments 15 and 19. In FIGURE 7 the RFinput compartment is not seen, but is understood to be behind thepartition 115.`

The associated electrical components are attached and otherwise wired-inon the top-plate assembly 110: the tube sockets (not shown), tubeshields, trimmer condensers, feed-through terminals, coils, resistors,fixed capacitors, and the zig-zag fixed long lines, as indicated in FIG-URE 7. The assembly is in the open, where readily accessible for wiring,soldering, and testing as a whole. All the feed-through units can beoven soldered before component wiring-in. The sub-assembly 110 can bemade on aline basis, as an ordinary radio or television chassis, with nodeep cavity work or critical positioning of parts.

In a similar way the U-assembly (FIGURE 9) can be made as a conventionalsub-assembly operation. The three-gang variable condenser section is rstmade as two units: the rotor plates secured to the tuning shaft 85; thestator Yblade groups 41a, 46a, 55a soldered onto silvered bands 81,82,83 respectively on ceramic rod 90. These two condenser units arereadily jigged-up for precise assembly. With suitable locating grooves,the shaft 85 and rod 90 can be automatically'positioned in the U-bracket120 sub-assembly between walls 40, 50. The feed-through terminals as 61,62, 121, 122 are mounted on the walls, and oven soldered prior tothecondenser assembly.

Two silver bands 123, 124 centrally of rod 90 permit ready soldering-inof the rod to the U-bracket walls 40, 50. Accurate condenser finalassembly and testing is thus readily feasible, inthe open instead of ina crowded interior. A slotted opening 42 (FIGURE 9) in wall 40 ispredeterminedly shaped fora desired degree of intercoupling between theRF output and mixer compartments v16, 17. Stiff metal ribbons 125, 126,127 extend from the three stator plate-sections towards adjacent portionwalls 40, 50 to establish the adjustable condensers or trimmers at therespective ends of the long-lines 36, 43,. 52

rURE 7).and 120 (FIGURE 8) are then Ymechanically fitted together, withtop plate 35 forming a T over the U-.bracket Projections or tabs as 130,131, 132 of bracket 120 .seat into or interlock with corresponding slotsinV plate 35, and are secured by soldering (see FIG. 4). The fewremaining electrical interconnections, between the two sub-assemblies,are thereupon completed in the open,

and the unit tested as a whole consistent single, and uniformperformance is readily attained in production runs by this invention,Yan advantageous result in compact devices.

yFIGURES 11 and V12`schematically illustrate the re- Y' maining assemblyof the invention tuner.r A rectangular vbox-like form 135 isinter-assembled with the T assembly 110, 120. Projections or tabs as136, 137, 13S (see FIG- URES 4 and 12) fit into slots in top-plate 35,to complete circuit compartments 16, 17 and 18. Also the compartmentsand 19 are completed against wall 30. The tabs-in-slots are soldered.Also, an aperture 141 in the rear wall 140 of unit 135 is located behindsolid rear wall 142 of the U-bracket 120. The two rear walls 1419, 142are soldered together with excess soldered locked in aperture 141. Withthe cover 100 afiixed to the thus assembled unit, the compartments arefully electrically isolated and enclosed on six sides each.

Although the present invention has been described in connection with anexemplary embodiment, it is to be understood that modifications thereofmay be made without departing from the broader aspects and spiritthereof as set forth in the following claims.

I claim:

1. A Ul-lli` tuner assembly comprising first and second sub-assemblies;

said first and second sub-assemblies including intersecting wallscombinedly defining a plurality of predetermined shield compartmentsthat isolate circuit sections of the tuner;

said first sub-assembly including a top plate, extending in a firstdirection and overlapping the end regions of at least some of saidpredetermined shield compartments, to form the shielded top Wallsthereof; said top plate receiving associated circuit components mountedthereto, while disassociated from said second sub-assembly, andconstructed to provide accessibility of said associated circuitcomponents during the mounting and assembly thereof;

said second sub-assembly including a U-bracket having two spacedpartition walls and a rear wall therebetween;

said partition walls parallel extending transverse to said top plate,and intersecting said top plate to define the shielded side boundariesbetween adjacent ones of said shield compartments;

a multi-ganged variable condenser means supported across said partitionwalls; Y

said multi-ganged variable condenser means having first means forsupporting the stator plates thereof, and second means for supportingthe rotor plates thereof;

said first and second means mounted to said U-bracliet for sub-unitassembly and subsequent incorporation as an integral unit intocooperative seating engagement with said first sub-assembly;

said first and second means positioning their respective condenser platefor location Within respective ones of said adjacent shield compartmentsupon the interengagement of said first and second sub-assemblies;

means for cooperatively interconnecting said assembled first and secondsub-assemblies to form said predetermined shield compartments containingsaid associated circuit components and respective portions of saidmulti-ganged variable condenser means.

2. A UHF tuner as set forth in claim l,

Said first and second sub-assemblies being mechanically joined into aT-like structure with said associated circuit components, and variablecondensers being interwired to substantially complete the tunercircuitry.

3. A tuner as claimed in claim l', in which said top-plate extendsbeyond said box-like unit with a reentrant section that coacts with theadjacent unit end wall to form a further circuit compartment.

4. A UHF tuner as set forth in claim 1, further including a cover plate,said cover plate including a wire mesh coextensive therewith and firmlypressed against the edges of said shield compartment, including saidpartition walls defining the boundaries between adjacent ones of saidcompartments, to effectively isolate said compartments.

5. A tuner as claimed in claim 4, in which said topplate extends beyondsaid box-like unit with a reentrant section that coacts with theadjacent unit end wall to form a further compartment for the RF inputcircuit section.

6. A UHF tuner assembly comprising first and second sub-assemblies;

said first and second sub-assemblies including intersecting wallscombine-diy defining a plurality of predetermined shield compartmentsthat isolate circuit sections of the tuner; Y

said first sub-assembly including a top plate, extending in a firstdirection and overlapping the end regions of at least some of saidpredetermined shield compartments, to form the shielded top wallsthereof;

said top plate receiving associated circuit components f mountedthereto, while disassociated from said second sub-assembly, andconstructed to provide accessibility of said associated circuitcomponents during the mounting and assembly thereof;

said second sub-assembly including a U-bracket having two spacedpartition walls and a rear wall therebetween;

said partition walls parallel extending transverse to said top plate,and intersecting said top plate to define the shielded .side boundariesbetween adjacent ones of said shield compartments;

a multi-ganged variable condenser means supported as an integral unitinto cooperative `seating engage` ment with said first sub-assembly;

said first and second means positioning their respective condenser platefor location within respective ones of said adjacent shield compartmentsupon the interengagement of said first and second sub-assemblies;

means for cooperatively Vinterconnecting said assembled first and secondsub-assemblies to form said predetermined shield compartments containingsaid associated circuit components and respective portions of saidmulti-ganged variable condenser means;

said first and second sub-assemblies being mechanically joined into aT-lilre structure with said associated circuit components, and variablecondensers being interwired to substantially complete the tunercircuitry;

a cover plate, said cover plate including a wire mesh coextensivetherewith and firmly pressed against the edges of said shieldcompartment, including said partition walls defining the boundariesbetween adjacent ones of said compartments, to effectively isolate saidcompartments.

7. In a tuner assembly of the character described, a shielded RF. inputsection, a shielded KF. output section electrically coupled to saidinput RF. section, a mixer compartment comprising a first shielding wallelectrically coupled to said output RP. compartment, said last mentionedcoupling comprising an aperture of a given a-rea in said first shieldwall between said mixer and said output RF. compartment, an oscillatorsection comprising a second shielding wall electrically coupled to saidmixer co., partment and a shielded LF. compartment electrically coupledto said oscillator compartment, said first and second shielding wallsparallel extending and joined by a connecting wall to define aU-bracket; said U-bracket constituting a sub-assembly for efiicientlyshieldingadjacent ones of said sections; said U-bracket carrying circuitcomponent independently mounted while said sub-assembly is disassociatedfrom said tuner assembly.

8. ln a tuner assembly of the character described, a shielded RE. inputsection, a shielded R.F. output section electrically coupled torsaidinput RF. section, a mixer compartment comprising a first shielding wallelectrically coupled to output RF. compartment, said last mentionedcoupling comprising an aperture of a given area in said irst shield wallbetween Ysaid mixer and said output Rf. compartment, an oscillatorsectioncornprsing a second shielding wall electrically coupled to saidmixer compartment and a shielded I F. compartment electrically coupledto said oscillator compartment, said last mentioned electrical couplingcomprising feed-through capacitors, said first and second shieldingwalls parallel extending and joined by a connecting wall to deiine aU-bracket; said U-bracket constituting a sub-assembly for efficientlyshieldingV adjacent ones of said sections; said U-bracket carryingcircuit component independently mounted while said sub-assembly isdisassociated from said tuner assembly.

1 9. In a tuner assembly'of the character described, an R.F. inputsection, an RP. output section, a shield between said sectionscomprising a shielding wall and a triode, said Wall and triode togethershielding said input section from said output RF. section andelectrically coupling said input RF. section and said output RF.section, a mixer compartment comprising a rst shielding Wallelectrically coupled to said output `RF. compartment, said lastmentioned coupling comprising an aperture'of a given area in said iirstshield Wall between said mixer and said output RF. compartment, anoscillator Vsection comprising a second ,shielding wall electricallycoupled to said mixer compartment and a shielded LF. compartmentelectrically coupled to said oscillator compartment, said irst andsecond shielding walls parallel extending and joined by a connectingwall to definel a U-bracket; said yU-bracket constituting a sub-assemblyfor eiciently shielding adjacent ones of said sections; said U-bracketcarrying circuit component independently Ymounted While saidsub-assembly is disassociated from said tuner assembly. Y

l0.V In a tuner assembly of the character described, an

KF. input section, an KF. output section, a shield be-V tween saidsections comprising a shielding wall and a triode, said wall and triodesection from said output RF. section and electrically coupling saidinput' RJ?. section, a mixer compartment comprising a iirst shieldingwallelectrically coupled to said output'RJF.V compartment, said lastmentioned coupling comprising an aperture of a given area'in said firstshield wall between said mixer and said output R.F. compartment, anoscillator section comprising a second shielding wall electricallycoupled to said mixer compartment and a shielded LF. compartmentelectrically coupled to said oscillator compartment, said shield between-said mixer and oscillator section comprising a triode acting incooperation With said second shield `wall for providing said shieldYbetween said compartments, said irst and ysecond shielding wallsparallel extending and joined by a connecting wall to define aU-bracket; said U-bracket constituting a sub-assembly for eicientlyshielding adjacent ones of said sections; said U-bracket carryingcircuit component independently mounted while said sub-assembly isdisassociated from said tuner assembly.

Beierences Cited by tire Examiner UNITED STATES PATENTS DAvrD G.REDINBAUGH, Primm Examiner- HARRY GAUSS, HERMAN K. SAALBACH,

' Examiners.

together shielding said input

1. A UHF TUNER ASSEMBLY COMPRISING FIRST AND SECOND SUB-ASSEMBLIES; SAIDFIRST AND SECOND SUB-ASSEMBLIES INCLUDING INTERSECTING WALLS COMBINEDLYDEFINING A PLURALITY OF PREDETERMINED SHIELD COMPARTMENTS THAT ISOLATECIRCUIT SECTIONS OF THE TUNER; SAID FIRST SUB-ASSEMBLY INCLUDING A TOPPLATE, EXTENDING IN A FIRST DIRECTION AND OVERLAPPING THE END REGIONS OFAT LEAST SOME OF SAID PREDETERMINED SHIELD COMPARTMENTS, TO FORM THESHIELDED TOP WALLS THEREOF; SAID TOP PLATE RECEIVING ASSOCIATED CIRCUITCOMPONENTS MOUNTED THERETO, WHILE DISASSOCIATED FROM SAID SECONDSUB-ASSEMBLY, AND CONSTRUCTED TO PROVIDE ACCESSIBILITY OF SAIDASSOCIATED CIRCUIT COMPONENTS DURING THE MOUNTING AND ASSEMBLY THEREOF;SAID SECOND SUB-ASSEMBLY INCLUDING A U-BRACKET HAVING TWO SPACEDPARTITION WALLS AND A REAR WALL THEREBETWEEN; SAID PARTITION WALLSPARALLEL EXTENDING TRANSVERSE TO SAID TOP PLATE, AND INTERSECTING SAIDTOP PLATE TO DEFINE THE SHIELDED SIDE BOUNDARIES BETWEEN ADJACENT ONESOF SAID SHIELD COMPARTMENTS; A MULTI-GANGED VARIABLE CONDENSER MEANSSUPPORTED ACROSS SAID PARTITION WALLS; SAID MULTI-GANGED VARIABLECONDENSER MEANS HAVING FIRST MEANS FOR SUPPORTING THE STATOR PLATESTHEREOF, AND SECOND MEANS FOR SUPPORTING THE ROTOR PLATES THEREOF; SAIDFIRST AND SECOND MEANS MOUNTED TO SAID U-BRACKET FOR SUB-UNIT ASSEMBLYAND SUBSEQUENT INCORPORATION AS AN INTEGRAL UNIT INTO COOPERATIVESEATING ENGAGEMENT WITH SAID FIRST SUB-ASSEMBLY; SAID FIRST AND SECONDMEANS POSITIONING THEIR RESPECTIVE CONDENSER PLATE FOR LOCATION WITHINRESPECTIVE ONES OF SAID ADJACENT SHIELD COMPARTMENTS UPON THEINTERENGAGEMENT OF SAID FIRST AND SECOND SUB-ASSEMBLIES; MEANS FORCOOPERATIVELY INTERCONNECTING SAID ASSEMBLED FIRST AND SECONDSUB-ASSEMBLIES TO FORM SAID PREDETERMINED SHIELD COMPARTMENTS CONTAININGSAID ASSOCIATED CIRCUIT COMPONENTS AND RESPECTIVE PORTIONS OF SAIDMULTI-GANGED VARIABLE CONDENSER MEANS.